Duplex pump or blower



(Ne Medel.) 8 sheets-sheen 1l.

J. 130W. Y DUPLEX PUMP OR BLOWER.

Ne. 878,042.A Patented feb; 14, 1888.

(No Medel.) 3 sneetssheee 2'.

,- J.,D0W..

DUPLEX PUMP 0R' BLOWER.

Patented Feb. l14, `1888.`

(No Model.) 3 sheets-sheet a'.

Y J. DOW

DUPLEX PUMP 0R BLOWER.

No. 378,042. Patented' Peb. 14, i888.'

I l l l l L `concussive action of the piston.

- UNITED STATES PATENT OFFICE.

JOSIAH Dow, on LoWELL, MASSACHUSETTS,

DUPLEX PUMP 0R BLOWER.

SPECIFICATION forming part of Letters Patent No. 378.042, dated February-14, 1888.

Application filed October 28, 1886. Serial No. 217,442. (No model.)

To aZZ whom it may concern.-

Be it known that I, JOSIAH DOW, a citizen of the 'United States, residing at Lowell, in the county of Middlesex and State of lMassachusetts, have invented new and useful Improvements in'Duplex Pumps or Blowers, of which the following is a specification.

The present invention relates to improvements upon the duplex rotary piston pump or blower for force or exhaust purposes for'which I have procured Letters Patent dated J une 2, 1885, No. 318,968. In said patent the pumpcylinder is cast with a vertical division-wall extending from top to bottom, except as to an opening receiving the piston-cylinders, thereby rendering it'necessary to construct the two abutment-valves in separate parts independently mounted on their central shaft, in order that they may be separately introduced into the piston-cylinder from opposite sides thereof. In the present invention the partition is of a special form, and the abutment valves are made in one piece,and can be fitted into place from either end of the casing, so as to cover both compartments of the pistonicylinde'r. In my former patent the fluids forced or drawn through the pump are liable to be retained in the cut-away portion of the abutment-valve and to produce a pocketing which effects a These objections it is the object of the present invention to avoid. Furthermore, in my former patent it was not possible to establish suction and to sustain high pressures with air, water, or fluids, whereas in the present invention, by a simple disposition of a valve or valves placed in the discharge-pipe, I am enabled to avoid the objections stated. V

The invention will first be fully described in connection with the accompanying drawings, and then clearly set forth in the claims.

Figure 1 is a longitudinal sectional view of a duplex rotary piston-pump embodying my improvements. Fig-2 isa' transverse section representing in front View the rotary piston and abutment-valve. Fig. 3 is a transverse sectional view representing the relative positions of the piston and abutment-valve when the former is about to enter the latter. Fig, 4 is a detail view showing the piston entered within the abutmentvalve. Fig. 5 is a detail View of the abutment-valves constituting an integral member or body. Fig. 6 is a view ot' the pump-casing, showing the partition in elevation.

The reference-numeral l designates the shell or casing of my pump, which is divided into two parallel chambers, 2 and 3, by meansof a vertical partition,4. This partition commences at the top of thecasing l, and is continued through the pipe 6 to the seat of the valve or valves 5, which are'placed in or near the opening of a pipe, 6, extending from the side ofthe shell 1. Below the main part of the partition located above the discharge-opening 5 the partition is continued in the form of a rim or ridge, 4, which extends around the circumference of the shell l and joins the upper part y vof the partition'. Referring to Fig. 6, the shape of the partition 4 is clearly seen, and it will be apparent that it has an upper circular open-- stituting, in connection with the rim or ridge f 4f and bottom of the shell 1,' a seat fori the revolving abutments. Y

The rim or ridge 4f, extending around the inner wall of the shell 1, is provided with recesses or grooves 7, which serve for the reception of a water or liquid packing,'as will be hereinafter fully set forth. rIhe revolving abutments (designated by the numerais 8 9) are constructed in one piece, as is seen in Figs. 1 and 5. They are made in the form of a cyl inder, which is of a uniform diameter throughout its entire length,and has cut-away portions 10 and 1l formed therein in diametricallybpposite directions. The cut-away portions constitute piston-openings which do not extend inder, pass from end to end, and other openings, markedl'onopposte sides ,of lthe center, stop at a partition, 16, in the center of the'A cylinder, said partition thus forming the in ner wall ot' the piston-openings. These two piston-openings or cut away portions of the abutment-cylinder end at the opposite sides of the partition 4, and form, in connection with the surface of said partition, a continuous bearing for the sides of the pistons 18 next to the center of the pump. The other sides of said pistons bear upon the heads of the case.

The piston-cylinder 19 is made in two sections, one carrying each piston 18, and they arejoincd together at the center of t'he partition 4, as is seen in Fig. 1. `The joining or abutting ends of the sections comprising the piston cylinder' are cut away from the outer circumference, and lap over the partition sut'- iiciently to allow't'nem to pass into the openA ing in the partition. As already stated, the abutment-cylinder can be placed into position from either end of the seat; but the pistoncylinder must be placed half-way from either end, not only on account of the presence of the pistons, but also by reason of the bearing of the piston cylinder in the partition 4. The pistons 18 project from the periphery of the piston-cylinder in diametrically-opposite directions,an.d co-operate with the corresponding cavities or openings in the abutment-cylinder in the same manner as in my former patent. The construction or shape ofthe pistons is, however,varied in the present instance in the following manner, viz: A thin wing, 25, passes back to the cylinder 19 from either lateral extremity of the face of the piston 18. The latter completely closes the annular chamber between the external or piston cylinder and shell 1, and is in thickness only about onehalf ofthe end of the piston and wing,whereas in my former patent this thickness was coequal with the whole end,which was narrower and rounded to lit more continuously in the piston-recessintheabutmentcylinder. When the end ofthe piston passes throughhe cutaway in the abutment, as is seen in Fig. 4, although the end of the wing as it enters said cut-away will fit its surface, as seen at x, the solid portion of the face will be at ashort distance from it, and will follow the dotted line y. At this time the other end of the cutaway, as at z, is about to open from contact with the piston-cylinder, the two revolving in opposite directions, as in my former patent. Before this opening takes place and until it is suicient to prevent it there would be a closed pocket for the contained fluid within the recess or cut-away and a hard impact of the piston would take place against it. These objectionable results are prevented, first, when the piston is in the position seen in Fig. 3 by leaving an opening, 35, at the top of a bridge, 30, located between the abutment-seat and the discharge, as at 3l,r for an outflow ofthe pocketed fluid into the discharge-pipe, and, second, after the piston has passed into the out away, as in Fig. 4, the opening around its end subserves the same purpose, commencing with stood that as soon as the solid portion or head of the piston passes up and out ofthe cut-away in the abutment-cylinder toward the point z it bears fully and begins its work again in forcing the water from the annular chamber, gradually working up to its full forcing as the opening increases at z. The operations just described prevent hard impacts, jarrings, and sudden changes of volume within the pump. It should be observed that the construction of the outer ends of both pistons 18 is-the same, and also the bridge at 35 for both chambers.

In order to establish suction and sustain high pressures with air,water, or other luid, I locate a valve or valves within the beginning of the discharge-pipe 6. This valve 40 may be a simple gate or flap-valve. which opens outwardly and bears against a seat located at the termination of the extension of the partition 4 within the discharge-pipe 6, said par tition coming down to the valve-seat. Iu-

stead of the valve shown, a flat partition` provided with one or more disks or other suitable "alve or valves may be arranged as seen' by the dotted line in Fig. 3. This latter form of valve would usually be the construction when the machineis used for an air-compressor or air-pump, iu order to permita closer compression. In either event each chamber of the piston-cylinder would have its separate valve or set of val ves, as one'side operates independently of the oiher,an l would take from the other when the open side of its piston was presented to the.discharge-opening, the pistons being opposed iu position.

The objectofthe valve or valves is as follows, viz: When the piston 18 is in the position shown in Fig. 3, the channel through itis open for a moment to the discharge-pipe. This causes ylittle or no diiculty after a flow of fluid has been established, except with very high pressures; but when air is in the pump the suction is lost at that momentV through its great elasticity. Therefore, in order to maintain the suction at vall pressures, to prevent back action from high pressure, and to make it possible to maintain high compression of air, the valves are resorted to. Referring again to the means for packing the abutment-,cylinder, I would state that in my former patent two movable packing-strips were located at the upper portion of the seat for the abutmentcylinder and relied upon to prevent the loss of fluid around the cylinder. In the present construction I omit the movable packingstrips and make use of a. water-packing confined and utilized as follows:

The abutment-cylinder has a close-fitting seat upon the ridge continuation of the partition 4. As already stated, continuous recesses are formed upon the inner face of the casing,

IIO

. fluid flowing from the main chambers around the abntments. v

In addition to packing the circumference of the abutment-cylinder with water or liquid, as just stated, I propose to pack the ends thereof in 'a similar manner, and 'for such object I provide the open-ended chambers of the abutmentcylinder. These chambers fit against the heads of the case and become iilled with iiuid, which revolves With the abutment'in a direct-ion opposed to the main current in the pump, and thus forms a packing which pre.

vents leakage across the ends of the abutmentcylinder. To still further decrease the liability ofleakagc, I make grooved channels 50 in the ends of the abutment-cylinder, which channels become filled with Water, as will be apparent.

It will be observed that since the abutmentcylinder moves in one direction and the piston-cylinder in another, as is indicated by the arrows in Fig. 3, the action of the fluid used as a packing andthat being forced through the pump will not partake of the saine revolving motions.

Having thus described my invention, what I claim is l. In a pump, the abutment-cylinder, made in asingle piece, having opposite alternatelyarranged peripheral openings or cavities, and provided with interior chambers the open ends of which lie against -the vertical Walls of the abutment-seat, substantially as described.

2. In a pump, the combination of the abutment-cylinder, made in one piece, and having recesses or cavities in its periphery, the casing or shell having a vertical partition and a rimshaped'bottomcontinuation thereof, and the detachable end heads, With the piston-cylin der bearing upon the abutment-cylinder, and having pistons adapted to Work in its cavities or recesses, substantially as herein set forth.

' 3. In a pump, the combination of the abutment-cylinder having peripheral cavities and openings extending from end to cnd with the casing and heads and the piston-cylinder, substantially as described. l

4. In a pump, the combination, withv the abutment-cylinder, having alternate and opposite peripheral cavities, and provided with grooves in its endsadapted to hold fluid for the purpose of packing, of the casing having a central packing-rib, the heads, and the pist0n-cylinder, the grooves in the said abutmentcylinder opening against the vertical walls of the abutmentseat, substantially as described. 5. 'Ihe combination, with the casing having an abutment seat and a discharge-pipe, of Va bridge-piece arranged bet-Ween the two, the

abutment-cylinder having peripheral cavities,

and the'piston-cyl'inder having pistons operat-` ing in said cavities, a relief-space being provided between the bridge-piece and the said pistons and between the pistons and the entrances of the peripheral openings of the abutment-cylinder, said spaces decreasing as the vstantially as described.

7. In a pump, the combination, with the casing [having a discharge -pipe upon one side, of the abutment-cylinder having peripheral openings, pistons co-operating with'the same, and a bridge intermediate between the discharge and the abutment cylinder, areliefspace being provided between said bridge and the piston, substantially as specified.

In testimony whereof I affix my signature'in presence of two witnesses. y

, Witnesses:

JAMEs L. NoRRIs, J. A. RUTHERFORD.

JosIAH DOW.' 

